Synthesis and characterization of mono- or di-valent cations substituted rare earth phosphates and their electrical properties.Abstract Substituted rare earth phosphates MREP MREP Medicare Remit Easy Print MREP Millirep [O.sub.4] [RE = La, Sm, Gd and M= Na and Ca] were prepared using two methods, the first method (I) is wet process and the other (II) is solid-solid reaction. All substituted RE phosphate compounds were analyzed by using inductively coupled plasma An inductively coupled plasma (ICP) is a type of plasma source in which the energy is supplied by electrical currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields. technique (ICP (1) (Internet Cache Protocol) A protocol used by one proxy server to query another for a cached Web page without having to go to the Internet to retrieve it. See CARP and proxy server. ) and characterized by infrared absorption spectra (IR), X-ray diffraction (XRD XRD X-Ray Diffraction XRD Crossroad XRD X-Ray Diode ) and scanning electron microscope scan·ning electron microscope n. Abbr. SEM An electron microscope that forms a three-dimensional image on a cathode-ray tube by moving a beam of focused electrons across an object and reading both the electrons scattered by the object and (SEM). The electrical conductivity Not to be confused with electrical conductance, a measure of an object's or circuit's ability to conduct an electric current between two points, which is dependent on the electrical conductivity and the geometric dimensions of the conducting object. also was measured for all prepared samples. The analysis of results indicates that there are a partially substitution for RE cations with mono- or di- cations. On other hand, different compounds, different phases and different structures such as layered, needle, slakes are formed depending on the method of preparation and type of cations. Keywords: Rare earth phosphates, preparation, characterization. Introduction Rare earth phosphates (REP[O.sub.4]) have an important properties such as their high melting points melting point, temperature at which a substance changes its state from solid to liquid. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and (up to 2300[degrees]C), high resistance towards the external oxidizing agents, high refractive indices Many materials have a well-characterized refractive index, but these indices depend strongly upon the frequency of light. Therefore, any numeric value for the index is meaningless unless the associated frequency is specified. and low solubility solubility Degree to which a substance dissolves in a solvent to make a solution (usually expressed as grams of solute per litre of solvent). Solubility of one fluid (liquid or gas) in another may be complete (totally miscible; e.g. in water. So they can be used as coating or composite matrices for high-temperature structural applications (1,2). A modification in the structure and the properties of rare earth phosphates can be carried out by substitution with other cations. This substitution may lead to improve some properties and has many effects on the other properties. In this field, it is found that the substitution by mono- and di-valent cations improve the electrical properties of the rare earth compounds more than tri-valent cations. A series of alkaline rare earth phosphates having the general formula [M.sub.3]RE(P[O.sub.4]) (M = Na, K, Rb and RE = La, Gd, Eu, Ce, Tb) was prepared by the reaction between freshly precipitated rare earth phosphate and alkaline metal Noun 1. alkaline metal - any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium); "the hydroxides of the alkali metals are strongly alkaline" alkali metal phosphate and carbonate as follows (3): [MATHEMATICAL EXPRESSION A group of characters or symbols representing a quantity or an operation. See arithmetic expression. NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. .] (1) On the other hand, [M.sub.3]RE[(P[O.sub.4]).sub.2] were usually prepared by solid state reaction from RE sesquioxides as powder or grown as crystals out of a flux of alkaline diphosphates (4,5) [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.] (2) But it is found that the preparation of [Rb.sub.3]RE[(P[O.sub.4]).sub.2] powders by these methods are very difficult because the double phosphates melt incongruently at about 1000[degrees]C (6). The formation of [M.sub.3]RE[(P[O.sub.4]).sub.2] double phosphates using monazite monazite (mŏn`əzīt), yellow to reddish-brown natural phosphate of the rare earths, mainly the cerium and lanthanum metals, usually with some thorium. Yttrium, calcium, iron, and silica are frequently present. type compounds as starting materials are not to be expected due to the melting temperatures Melting temperature may refer to:
adj. Of, containing, or involving an ion or ions. ionic pertaining to an ion or ions. ionic medication iontophoresis. radii ra·di·i n. A plural of radius. radii Noun a plural of radius affect in the measured conductivity conductivity /con·duc·tiv·i·ty/ (kon?duk-tiv´i-te) the capacity of a body to transmit a flow of electricity or heat; the conductance per unit area of the body. con·duc·tiv·i·ty n. 1. values. Previously, the author prepared Na, Al, Fe, Zn phosphates by both the traditional and sol- gel methods (8,9). Also, they prepared different samples of REP[O.sub.4] (RE = La, Gd, Sm) by using different methods and precursor materials (12). The present work aims to preparing substituted RE phosphates with mono- or di- valent cations ([Na.sup.+] and [Ca.sup.+2]) to study the effect of this substitution on the structural, growth of crystals, electrical properties of the produced samples. Experimental The preparation of REP[O.sub.4] (RE= La, Sm, Gd) by different methods where described elsewhere (13). On the bases of these method, the substitution with Na or Ca cations (in 0.3% mole as nitrates) was preceded by using two processes as: --Process (I) wet process --Process (II) solid--solid reaction Table (1) contains a brief description of the preparation methods. All the chemicals used were of analytical grade. The obtained products as produced were chemically analyzed by using inductively coupled plasma technique (ICP), and characterized by Infrared absorption spectroscopy Absorption spectroscopy refers to a range of techniques employing the interaction of electromagnetic radiation with matter. (Spectroscopy is a word that has come to denote an even wider variety of techniques used in physics and chemistry. (IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). IR spectra were performed by KBr method using Fourier transformer transformer, electrical device used to transfer an alternating current or voltage from one electric circuit to another by means of electromagnetic induction. (Nexus 670 FTIR FTIR Fourier Transform Infrared (spectroscopy) FTIR Frustrated Total Internal Reflection FTIR Fourier Transfer Ir , USA) over 400-4000 [cm.sup.-1]. The XRD patterns of the prepared samples were recorded using Brukur D8 advance diffractometer A Diffractometer (Main Entry: dif·frac·tom·e·ter Pronunciation: di-"frak-'tä-m&-t&r Function: noun) is a measuring instrument for analyzing the structure of a usually crystalline substance from the scattering pattern produced when a beam of radiation or particles (as X rays or (Germany) using Copper [K.sub.[alpha]]. radiation. The micrographs of powders were performed by SEM-JEOL JAX- 840 A (Japan). The electrical conductivity of the prepared samples was measured as a function of temperature using LCR See least cost routing. Hioki instrument (Japan). The frequency was adjusted at 50 KHz and applied voltage of 3 V. Results and Discussion Chemical analysis The results of chemical analysis for LaP[O.sub.4], GdP[O.sub.4], and SmP[O.sub.4] exhibit a non-stoichiometric ratio which depends on the method of preparation (13) Table (2a). For the substitution of REP[O.sub.4] with [Na.sup.+] or [Ca.sup.2+], NaN[O.sub.3] or Ca[(N[O.sub.3]).sub.2] was added with ratio = 0.3% mol to the medium of reaction as described in Table(1). The chemical analysis of the substituted samples Table(2b) shows that there is a decrease in the values of RE/P[O.sub.4] than that observed for pure REP[O.sub.4], this decrease depends on the method of preparation, nature of rare earth elements “Rare earth” redirects here. For other uses, see Rare earth (disambiguation). Rare earth elements and rare earth metals are a collection of sixteen chemical elements in the periodic table, namely scandium, yttrium, and fourteen of the fifteen lanthanoids and [Na.sup.+] or [Ca.sup.2+] cations. On other hand an appearance for M/P M/P Market Price M/P Maintenance Planning M/P Merry/Pippin (Lord Of The Rings) [O.sub.4] values (M=Na, Ca) was observed. This finding indicates that there are a partially substitution for RE by M cations, so mixed phases were produced. IR Spectrum Figures (1), (2) and (3) show the IR spectra of substituted RE phosphates. In general, Two absorption bands Noun 1. absorption band - a dark band in the spectrum of white light that has been transmitted through a substance that exhibits absorption at selective wavelengths optical phenomenon - a physical phenomenon related to or involving light attributed to OH/[H.sub.2]O vibrations were observed. The first one at ~3500 [cm.sup.-1] corresponding to residual OH groups, which remained after dehydration dehydration Method of food preservation in which moisture (primarily water) is removed. Dehydration inhibits the growth of microorganisms and often reduces the bulk of food. . The second one at ~1610-1620 [cm.sup.-1] probably associated with the water bending model as observed by Yan Guo (14) and Ben Mousa (15). Another postulation is that these bands may originate during the preparation of KBr discs by moisture attack of powdered materials. The specific absorption bands which characterized phosphate metal formation (16), P-O P-O Perfection-Oriented , O=P-O and O-P-O were observed. On other hand there [v.sub.as]P[O.sub.2], [v.sub.s]P[O.sub.2], [v.sub.as]P-O-P and [v.sub.s]P-O-P respectively indicating the formation of metaphosphate met·a·phos·phate n. A salt or an ester of metaphosphoric acid. salts (17). By substitution of RE phosphates with Na or Ca cations, it is observed that there are some changes in the position and intensity of peaks with splitting in some peaks such as [delta] P[O.sub.2] at 769 [cm.sup.-1]. This behavior may result from the difference in the ionic radius The ionic radius, rion, is a measure of the size of an ion in a crystal lattice. It is measured in either picometres (pm) or Angstrom (Å), with 1 Å = 100 pm. Typical values range from 30 pm (0.3 Å) to over 200 pm (2 Å). of metal cations as well as the change in the crystal size (18), beside the formation of metaphosphate salts as observed by Ilieva et al (17) [FIGURE 1 OMITTED] [FIGURE 2 OMITTED] X-ray diffraction For substituted RE phosphates, X-ray diffraction patterns diffraction pattern The interference pattern that results when a wave or a series of waves undergoes diffraction, as when passed through a diffraction grating or the lattices of a crystal. of the as-prepared powders indicate that there is a partially substitution of RE phosphates by either mono- or divalent divalent /di·va·lent/ (di-va´lent) bivalent; carrying a valence of two. di·va·lent adj. Bivalent. di·va cations (Na or Ca), new phases and new compounds are observed, figures (4), (5) and (6). In the case of LaP[O.sub.4] which is substituted by [Na.sup.+], a crystalline Like a crystal. It implies a uniform structure of molecules in all dimensions. For example, phase change technology, widely used for rewritable optical discs, uses crystalline spots (bits) to reflect the laser beam. Amorphous, non-crystalline bits do not reflect light. compound, o-NaLa[P.sub.2][O.sub.7], (JCPDS JCPDS Joint Committee on Powder Diffraction Standards : 21-113201) is observed when the solid- solid reaction was followed (method II), while in the case of wet method (I) a glassy amorphous Unorganized or vague. A lack of structure. For example, the amorphous state of a spot on a rewritable optical disc means that the laser beam will not be reflected from it, which is in contrast to a crystalline state which will reflect light. See crystalline. states, LaP[O.sub.4], La[P.sub.3][O.sub.9] and NaLa[(P[O.sub.3]).sub.4] were formed. In the case of substitution by [Ca.sup.+2], [Ca.sub.3][(P[O.sub.4]).sub.2] and [Ca.sub.8][La.sub.2][(P[O.sub.4]).sub.6][O.sub.2] were formed (19) in crystalline state by using method (II). An amorphous phase of La[P.sub.2][O.sub.9] and Ca[(P[O.sub.3]).sub.2] was formed by using method (I). [FIGURE 3 OMITTED] For substitution of SmP[O.sub.4] and GdP[O.sub.4] by [Ca.sup.2+] or [Na.sup.+] (figures 5 and 6), it is observed that, the crystallinity Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. In a gas, the relative positions of the atoms or molecules are completely random. of the produced phases improved by substitution with [Na.sup.+], while it tends to become amorphous in the case of [Ca.sup.+2]. Table (3) shows the methods of preparation, the produced phases of RE phosphates, their substituted derivatives, and the crystallinity of each product. Scanning electron microscope (SEM) For substitution of LaP[O.sub.4] with [Na.sup.+], the SEM graphs Fig.(7) indicate that the samples prepared by (method II) are more crystalline and transparent than that prepared by (method I). For substitution with [Ca.sup.+2], the samples prepared by (method II) exhibit a spongneous crystalline state but very clear fibers with matrix were formed by using (method I). This finding proves that wet method can be used to prepare needles or layered structure. [FIGURE 4 OMITTED] [FIGURE 5 OMITTED] In the case of SmP[O.sub.4], the substitution with [Na.sup.+], Fig. (8), the fine needle crystalline forms were observed by using method (I) or (II). In the case of [Ca.sup.2+] substitution a very fine crystals with matrix were observed by using solid-solid reaction (II), while a crystalline layered structure was observed in the case of method (I). For the images of SEM Fig. (9), in the case of substitution of GdP[O.sub.4] with Na+, transparent states with fiber textures were produced in the case of method (II), while they give a structure that looks like slakes by using method (I). The substitution with [Ca.sup.2+] gives fine structure with nearly amorphous matrix by using method (II) while a needle shape was observed in method (I). From these results, it may be concluded that the texture morphology morphology In biology, the study of the size, shape, and structure of organisms in relation to some principle or generalization. Whereas anatomy describes the structure of organisms, morphology explains the shapes and arrangement of parts of organisms in terms of such of the products greatly depend on the method of preparation. Electrical conductivity Phosphate based materials containing alkali metals alkali metals, metals found in Group 1 of the periodic table. Compared to other metals they are soft and have low melting points and densities. Alkali metals are powerful reducing agents and form univalent compounds. are interest for their ionic conductivity, which can easily reach values of the order of [10.sup.-2] [ohm ohm (ōm) [for G. S. Ohm], unit of electrical resistance, defined as the resistance in a circuit in which a potential difference of one volt creates a current of one ampere; hence, 1 ohm equals 1 volt/ampere. .sup.-1] [cm.sup.-1] near room temperature (20). For substitution of rare earth phosphates with [Na.sup.+] or [Ca.sup.2+], a mixture of compounds having different phases as confirmed by X-ray diffraction was produced. Therefore, the effect of the substitution on the electrical conductivity is so difficult to compare. The variation of the conductivity (*) with temperature is shown, figures (10) to (12), in spite of the absence of the homogeneity Homogeneity The degree to which items are similar. for the products. From these figures, it may be seen that all the phosphate compounds have the same trends as that observed for the pure phosphates where they have semiconducting properties also. [FIGURE 6 OMITTED] [FIGURE 7 OMITTED] As it is well known, that the introduction of mono- or di- valent cations increases the electrical conductivity (20,21). The recorded results exhibit some deviations from this knowledge. This deviation can be due to * values of the phosphates with low-doped contents which are partly lower than * of the undoped samples. This may due to a trap effect produced by a kind of recombination recombination, process of "shuffling" of genes by which new combinations can be generated. In recombination through sexual reproduction, the offspring's complete set of genes differs from that of either parent, being rather a combination of genes from both parents. of electrons with [H.sub.3][O.sup.+]ions and other impurity im·pu·ri·ty n. pl. im·pu·ri·ties 1. The quality or condition of being impure, especially: a. Contamination or pollution. b. Lack of consistency or homogeneity; adulteration. c. cations or between holes and impurity anions, respectively (22). It is also possible, however, that the doped dope n. 1. Informal a. A narcotic, especially an addictive narcotic. b. Narcotics considered as a group. c. An illicit drug, especially marijuana. 2. ions (Ca and Na) give rise to a hindrance hin·drance n. 1. a. The act of hindering. b. The condition of being hindered. 2. One that hinders; an impediment. See Synonyms at obstacle. of the ionic carriers by their strong complex formation and thus leads to a reduction of carriers mobility and conductivity. Conclusion Chemical analyses of substituted rare earth phosphates reveal that there is a decrease in RE/P[O.sub.4] ratio and there is a considerable values for [M.sup.+] or [M.sup.+2]/P[O.sub.4], this result indicates that there is a partially substitution of RE by M cations. The analyses of IR spectra for the prepared samples show that there are absorption bands characteristic to the P-O, O=P-O, O-P-O, specified to formation of the phosphate compounds. X-ray diffraction results in all cases show that the resulting compounds and their phases depend on the method of preparation, nature of additive materials and heat treatment. The morphology of the prepared samples indicates that the wet method can be used to prepare layered or needle structure. The electrical conductivity of the prepared samples shows that d* / dT has a positive increase with temperature indicating that the prepared samples have semiconducting properties. [FIGURE 8 OMITTED] [FIGURE 9 OMITTED] [FIGURE 10 OMITTED] [FIGURE 11 OMITTED] [FIGURE 12 OMITTED] References [1] Boakye, E., and Petry M. D., 1996, "Manufacture of Fiber-reinforced ceramic composites," Ceram. Eng. Sci. Proc., 17, pp. 53-59. [2] Cheng, P., and Mah, T. I., 1997" photocoustic, thermal characterization of porous porous /por·ous/ (por´us) penetrated by pores and open spaces. po·rous adj. 1. Full of or having pores. 2. Admitting the passage of gas or liquid through pores. rare earth phosphate ceramics," J.Mater. Sci., 32, pp. 3863-3868. [3] Schwarz, L., Kloss, M., Rohmann, A., Sasum, U., and Haberlandl, D., 1998, "Investigation of alkaline rare earth orthophosphates," J. Alloys and Compounds 93, pp. 275-277. [4] Van Wazer, J.P., 1962, "phosphorous phos·pho·rous adj. Of, relating to, or containing phosphorus, especially with a valence of 3 or a valence lower than that of a comparable phosphoric compound. and its compounds, Inter science," New York New York, state, United States New York, Middle Atlantic state of the United States. It is bordered by Vermont, Massachusetts, Connecticut, and the Atlantic Ocean (E), New Jersey and Pennsylvania (S), Lakes Erie and Ontario and the Canadian province of , 1, pp. 419. [5] Corbridge, D.E.C., 1978, "phosphorous, an outline of its Chemistry, Biochemistry, and Technology," Elsevier, Amsterdam, pp. 89, and 133. [6] Schwarz, L., 1985, B Thesis, Greifswald, [7] Corbridge, D.E.C., 1966,"Topics in phosphorous Chemistry," 3 (57) Editor: B.I. Griffith, pp. 167, 232, 247 and 255. [8] Khalil, M. Sh., Hanna, A. A., and El-sayed, M. A., 2002, "Sol-gel synthesis of AlP[O.sub.4] and FeP[O.sub.4]," Phos. Res. Bull, 12, pp. 77-90. [9] Khalil, M. Sh., Hanna, A. A., and El-sayed, M. A., 2002, "Synthesis of mono- or di- valent cations substituted Al or Fe- phosphates and their electrical conductivity," Phos. Res. Bull, 14, pp.77-88. [10] Szirtes, L., Megyeri J., Kuzmann E., Klencsar Z., 2001, "Electrical condyctivity of transition metal containing crystalline zirconium zirconium (zərkō`nēəm), metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.22; m.p. about 1,852°C;; b.p. 4,377°C;; sp. gr. 6.5 at 20°C;; valence +2, +3, or +4. phosphate materials," Solid State Ionics, 145, pp. 257-261. [11] Onoda, H., Takenaka, A., Kojima, K., and Nariai, H., 2005, "Temprature dependence on addition of urea and its related compounds on formation of neodymium neodymium (nē'ōdĭm`ēəm), metallic chemical element; symbol Nd; at. no. 60; at. wt. 144.24; m.p. about 1,021°C;; b.p. about 3,068°C;; sp. gr. 7.004 at 20°C;; valence +3. Neodymium is a lustrous silver-yellow metal. condensed con·dense v. con·densed, con·dens·ing, con·dens·es v.tr. 1. To reduce the volume or compass of. 2. To make more concise; abridge or shorten. 3. Physics a. phosphate," Material and Design 26, pp.711-716. [12] Hanna, A.A., Khalil, M.Sh., Mousa, S.M.A., and El-sayed, M.A., "Preparation and Characterization of Rare Earth Phosphates, 1- LaP[O.sub.4] and Its Electrical Properties," In press. [13] Takenaka, A., Sawa, H., Hirata, M., Yamamoto, A., Motooka, I., and Nariai, H., 1998,"Thermal products of sodium dihydrogen phosphate- urea mixtures and lithium lithium (lĭth`ēəm) [Gr.,=stone], metallic chemical element; symbol Li; at. no. 3; at. wt. 6.941; m.p. about 180.54°C;; b.p. about 1,342°C;; sp. gr. .534 at 20°C;; valence +1. Lithium is a soft, silver-white metal. carbonate- ammonium ammonium /am·mo·ni·um/ (ah-mo´ne-um) the hypothetical radical, NH4, forming salts analogous to those of the alkaline metals. ammonium carbonate dihydrogen phosphate- urea mixtures," Phos. Res. Bull. 8, pp. 107-112. [14] Guo, Y., Woznicki, P., and Barkatt, A., 1996, "Sol- gel synthesis of microcrystalline microcrystalline /mi·cro·crys·tal·line/ (-kris´tah-lin) made up of minute crystals. microcrystalline made up of minute crystals. rare earth orthophosphates," J. Mater. Res., 11(3), pp. 639-648. [15] Ben Mousa, S., Sobrados, Iglesias, I., Trabelsi-Ayedi, J. E., M., and Sanz, J., 2000, "Synthesis and characterization of hydrated hy·drat·ed adj. Chemically combined with water, especially existing in the form of a hydrate. Adj. 1. hydrated - containing combined water (especially water of crystallization as in a hydrate) hydrous rare earth acid diphosphates," J. Mater. Chem., 10, pp. 1973-1978. [16] Klee, W. E. and Engel, G., 1970, "Infrared spectra of the phosphate ions in various apatite apatite (ăp`ətīt), mineral, a phosphate of calcium containing chlorine or fluorine, or both, that is transparent to opaque in shades of green, brown, yellow, white, red, and purple. ," J. Inorg. Nucl. Chem., 32, pp. 1837-1844. [17] Ilieva, D., Kovacheva, D.,Cole, J. M.,and Gutzow, I., 2002, "Structure and devirtifcation chemistry of RE[(P[O.sub.3]).sub.3]," Phos. Res. Bull., 13, pp.137-146. [18] Corl, E. A., Silverman, S. L., and Kim, Y. S., 1966, "Nodestructive detection of P oxide layers on semiconductor wafers," Solid-State Electron, 9, pp.1009-1015. [19] Horchani, K., Ferid, M., and Trabelsi-Ayedi, M., 2001, "Chemical preparation and thermal behavior of a new sodium neodymium cyclotriphosphate, " Mater. Res. Bull., 36(5-6), pp. 897-903. [20] Mustarelli, P., 1999, 3rd Inter. Sym. On Inorganic inorganic /in·or·gan·ic/ (in?or-gan´ik) 1. having no organs. 2. not of organic origin. in·or·gan·ic n. 1. phosphate materials, Villeneure,d, Ascq, France, 14-16th Sept. [21] Laghzizil, A., Bauhaouss, A., and Ferhat, M., 1999, 3rd Inter. Sym. on Inorganic phosphate materials, Villeneure,d, Ascq, France, 14-16th Sept. [22] Zirkelbach, K. and Bruchner, R., 1988, "Electrical conductivity of semiconducting barium barium (bâr`ēəm) [Gr.,=heavy], metallic chemical element; symbol Ba; at. no. 56; at. wt. 137.33; m.p. 725°C;; b.p. 1,640°C;; sp. gr. 3.5 at 20°C;; valence +2. aluminophosphate glasses containing single and double redox redox (rē`dŏks): see oxidation and reduction. pairs," Glstechnische Berichte, International J. of glass, Sci, and Tech. 61, pp.12-23. A.A. Hanna, A.F. Ali, S.M.A. Mousa and M.A.EL-Sayed Inorg. Chem. Dept., National Research Centre, Dokki, Cairo, Egypt
Table 1: Methods of preparation of substituted RE phosphates.
Compound Input
material
MREP[O.sub.4] R[E.sub.2]
0.3:0.7:1 [O.sub.3.
M=Na, Ca sup.+]
RE=(La,Sm, Gd)
(process I) MN[O.sub.3.
sup.+]
(3N)HN[O.sub.
3.sup.+]
(N[H.sub.4])
[H.sub.2]P
[O.sub.4]
(process) R[E.sub.2]
(II) [O.sub.3.
sup.+]
MN[O.sub.3.
sup.+]
(N[H.sub.4])
[H.sub.2]P
[O.sub.4]
Compound Methods of Product
preparation form
MREP[O.sub.4] For preparing sodium or calcium Very fine
0.3:0.7:1 substituted samples, R[E.sub.2] powder
M=Na, Ca [O.sub.3] and MN[O.sub.3] with
RE=(La,Sm, Gd) known percent were added to
(process I) HN[O.sub.3] for dissolving,
then [(N[H.sub.4]).sub.2] [H.sub.2]
P[O.sub.4] (30%) was added dropwise
to produce a white suspend gel,
the product was leaved in water
path at 75[degrees] C for 2 hr and
then dry at 130[degrees]C for
6 hr and at 300[degrees]C for 6 hr then
fired at 850[degrees] C for 4 hr
(process) The three compounds were mixed White
(II) thoroughly for 2 hr in desired crystal
properties as produced in
preparation by solid- solid
reaction and fired at 1300
[degrees]C for 2hr
Table 2a: Chemical analysis of REP[O.sub.4], (RE=La, Sm, Gd)
Element
Comp. Method RE=La,Sm, Gd%
LaP[O.sub.4] I Theo 59
Exp 52.89
LaP[O.sub.4] II Theo 59
Exp 62.37
SmP[O.sub.4] I Theo 61.2
Exp 30.24
SmP[O.sub.4] II Theo 61.2
Exp 48.02
GdP[O.sub.4] I Theo 62.3
Exp 42.92
GdP[O.sub.4] II Theo 62.3
Exp 5.19
Element Element
P[O.sub.4]% RE/P[O.sub.4]
Theo 40.5 1.46
Exp 66.64 0.794
Theo 40.5 1.46
Exp 34.5 1.81
Theo 38.77 1.58
Exp 66.86 0.452
Theo 38.77 1.58
Exp 36.33 1.32
Theo 38.77 1.61
Exp 46.85 0.92
Theo 38.77 1.61
Exp 4.91 1.06
Table 2b: Chemical analysis of substituted REPO4, (RE=La, Sm, Gd)
Comp. Method Na/Ca
=M %
LaNaP[O.sub.4] I Theo 3.46
Exp 1.85
LaNaP[O.sub.4] II Theo 3.46
Exp 4.11
LaCaP[O.sub.4] I Theo 5.9
Exp 0.44
LaCaP[O.sub.4] II Theo 3.34
Exp 0.77
SmNaP[O.sub.4] I Theo 3.34
Exp 4.61
SmNaP[O.sub.4] II Theo 3.34
Exp 4.61
SmCaP[O.sub.4] I Theo 5.66
Exp 1.43
SmCaP[O.sub.4] II Theo 5.66
Exp 2.83
GdNaP[O.sub.4] I Theo 3.26
Exp 1.01
GdNaP[O.sub.4] II Theo 3.26
Exp 1.7
GdCaP[O.sub.4] I Theo 5.53
Exp 0.82
GdCaP[O.sub.4] II Theo 5.53
Exp 0.47
Element
P[O.sub.4] % M/P[O.sub.4] RE/P[O.sub.4]
Theo 47.69 0.072 1.024
Exp 59.4 0.031 0.746
Theo 47.69 0.0725 1.024
Exp 36.05 0.114 1.5
Theo 47.69 0.123 1.024
Exp 72.47 0.0061 0.451
Theo 47.69 0.123 1.024
Exp 40.59 0.02 1.37
Theo 38.77 0.086 1.309
Exp 69.6 0.011 0.41
Theo 38.77 0.086 1.309
Exp 42.21 0.109 1.12
Theo 38.77 0.146 1.277
Exp 65.44 0.022 0.42
Theo 38.77 0.146 1.277
Exp 42.21 0.076 0.842
Theo 38.77 0.084 1.39
Exp 22.82 0.044 0.37
Theo 38.77 0.084 1.39
Exp 14.27 0.119 1.0
Theo 38.77 0.143 1.31
Exp 0.82 0.017 0.65
Theo 38.77 0.143 1.31
Exp 0.47 0.06 1.16
Table 3: Phases of the produced REPO4 and their substituted.
Samples Method Phases
LaP[O.sub.4] I (350[degrees] C) LaP[O.sub.4], La[P.sub.7]
LaP[O.sub.4] I (850[degrees] C) La[P.sub.3][O.sub.9],
LaP[O.sub.4] monazite
LaP[O.sub.4] +Na I LaP[O.sub.4], La[P.sub.3]
[O.sub.9],
NaLa[(P[O.sub.3]).sub.4]
LaP[O.sub.4] +Ca I La[O.sub.3][O.sub.9],
Ca[(P[O.sub.3]).sub.2]
LaP[O.sub.4] II LaP[O.sub.4]
LaP[O.sub.4]+Na II O-Na-La[P.sub.2][O.sub.7]
LaP[O.sub.4]+Ca II [Ca.sub.8][La.sub.2]
[(P[O.sub.4]).sub.6]
[O.sub.2], CaP[O.sub.4]
SmP[O.sub.4] I (350[degrees] C) SmP[O.sub.4]
0.5[H.sub.2]O,
Sm[([H.sub.2]
P[O.sub.2]).sub.3]
SmP[O.sub.4] I (850[degrees] C) SmP[O.sub.4]
SmP[O.sub.4] +Na I SmP[O.sub.4],
[Na.sub.3]P[O.sub.4]
SmP[O.sub.4] +Ca I SmP[O.sub.4],
u-Ca[(P[O.sub.3]).sub.2]
SmP[O.sub.4] II SmP[O.sub.4] monazite
SmP[O.sub.4] +Na II [Na.sub.4]Sm[(P[O.sub.4])
.sub.5][P.sub.2][O.sub.7]
SmP[O.sub.4] +Ca II [Ca.sub.8][Sm.sub.2]
[(P[O.sub.4]).sub.6]
[O.sub.2],SmP[O.sub.4]
monazite, [Ca.sub.3]
[(P[O.sub.4]).sub.2]
GdP[O.sub.4] I GdP[O.sub.4]
GdP[O.sub.4] +Na I GdP[O.sub.4],Gd[P.sub.5],
[(NaP[O.sub.3]).sub.4]
GdP[O.sub.4] +Ca I [Ca.sub.8][Gd.sub.2]
[(P[O.sub.4]).sub.6]
[O.sub.2]
GdP[O.sub.4] II GdP[O.sub.4]
GdP[O.sub.4] +Na II [Na.sub.3]Gd[(P[O.sub.4])
.sub.2], GdP[O.sub.4]
GdP[O.sub.4] +Na II [Ca.sub.8][Gd.sub.2]
(P[O.sub.4])[O.sub.2],
GdP[O.sub.4]
Samples Morphology
LaP[O.sub.4] Little crystalline
LaP[O.sub.4] Amorphous
LaP[O.sub.4] +Na Amorphous- glassy
state
LaP[O.sub.4] +Ca Little crystalline-
fiber
LaP[O.sub.4] Crystalline
LaP[O.sub.4]+Na Crystalline
LaP[O.sub.4]+Ca Crystalline
SmP[O.sub.4] Amorphous-
transparent
SmP[O.sub.4] Crystalline
SmP[O.sub.4] +Na Crystalline- small
size
SmP[O.sub.4] +Ca Little crystalline-
glassy state
SmP[O.sub.4] Little crystalline
Decrease
SmP[O.sub.4] +Na crystallinity- fine
crystal
SmP[O.sub.4] +Ca More decrease of
crystallinity
--glassy state
GdP[O.sub.4] Crystalline
GdP[O.sub.4] +Na Mainly amorphous
GdP[O.sub.4] +Ca Crystalline- glassy
state
GdP[O.sub.4] Amorphous
GdP[O.sub.4] +Na Little increase in
crystallinity
GdP[O.sub.4] +Na Amorphous--needle
shape
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