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Correlation between structure, chromaticity, and dielectric properties of calcium copper pyrophosphates, Ca2−xCu xP2O7
(2022-12-01)
Baitahe, Rattanai
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Sronsri, Chuchai
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Thompho, Somphob
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Chaiseeda, Kittichai
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Montri, Nattaya
The solid-state reaction was employed to synthesize Ca<inf>2−x</inf>Cu<inf>x</inf>P<inf>2</inf>O<inf>7</inf> by varying the mole ratio between Ca and Cu. The structure and crystallography of the pyrophosphate compounds were identified and confirmed by using X-ray diffraction (XRD). The Rietveld refinement method and the extended X-ray absorption fine structure (EXAFS) least-squares fitting technique were also applied to refine the sample crystal structure. The single phases of the obtained Ca<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, CaCuP<inf>2</inf>O<inf>7</inf>, and Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf> samples and the mixing phases of the obtained Ca<inf>1.5</inf>Cu<inf>0.5</inf>P<inf>2</inf>O<inf>7</inf> and Ca<inf>0.5</inf>Cu<inf>1.5</inf>P<inf>2</inf>O<inf>7</inf> samples were identified, and then only a single phase of the samples was subjected to structural and dielectrical analyses. The structural results exhibit the tetragonal crystal system with the P4<inf>1</inf> space group for β-Ca<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, the monoclinic crystal system with the P2<inf>1</inf>/c space group for CaCuP<inf>2</inf>O<inf>7</inf>, and the C2/c space group for α-Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>. The dielectric constant (ε<inf>r</inf>) of the single metal pyrophosphates (Ca<inf>2</inf>P<inf>2</inf>O<inf>7</inf> and Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>) was higher than that of binary metal pyrophosphates (CaCuP<inf>2</inf>O<inf>7</inf>). The image sensor result of the Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf> sample (x = 2.00) illustrated a yellowish-green color, while other compounds (x = 0.50−1.50) presented color tones that changed from blue-green to bluish-green. Raman and Fourier transform infrared (FTIR) spectrophotometers were employed to characterize and confirm the vibrational characteristics of the P<inf>2</inf>O<inf>7</inf>4− group, which contains the O–P–O radical ([PO<inf>2</inf>]-) and the P–O–P bride ([OPO]-) and approximate M–O stretching modes. Furthermore, this work reports for the first time that the change in the crystal structure of Ca<inf>2−x</inf>Cu<inf>x</inf>P<inf>2</inf>O<inf>7</inf> (i.e., bond angle of P−O−P in P<inf>2</inf>O<inf>7</inf>4− and distortion phenomena in the M−O<inf>6</inf> octahedral site) are cause the correlation between the structure, chromaticity, and dielectric properties of calcium copper pyrophosphates, Ca<inf>2−x</inf>Cu<inf>x</inf>P<inf>2</inf>O<inf>7</inf>.
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A Simple Synthesis, Characterization, Kinetics and Thermodynamics of Zinc Ammonium Phosphate, ZnNH4PO4
(2020-03-01)
Baitahe, Rattanai
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Boonchom, Banjong
Zinc ammonium phosphate (ZnNH<inf>4</inf>PO<inf>4</inf>) was synthesized via a simple precipitation method at room temperature. Thermal decomposition of ZnNH<inf>4</inf>PO<inf>4</inf> occurred through five stages related to the deamination (1st and 2nd steps) and deprotonated hydrogen phosphate (3rd, 4th, 5th steps) reactions and its final decomposed product at above 600 °C was zinc pyrophosphate (to γ-Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>). ZnNH<inf>4</inf>PO<inf>4</inf> and γ-Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf> samples were analyzed by XRF, XRD, FT-IR and SEM techniques, which are significant for the further treatments. Kinetic parameters (E<inf>a</inf>, A) and thermodynamic functions (ΔH*, ΔS* and ΔG*) calculated on well-known equations have been used to support for five thermal transformation processes, reported for the first time. The kinetic results indicate that the intramolecular dehydration of the protonated hydrogen phosphate groups (3rd, 4th, 5th steps) need higher-energy pathways than the deammonium reactions (1st and 2nd steps) because of harder reactions, more difficulties and lower rates. Additionally, thermodynamic results reveal that all thermal reactions are endothermic and non-spontaneous processes. The obtained data may be useful for industrialists and academicians to apply these zinc phosphates for large roles in industrial applications.
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The effect of zirconium on the perovskite phase formation of barium zirconium titanate nanoparticles by the sonochemical method
(2016-01-26)
Wirunchit, Supamas
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Baitahe, Rattanai
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Vittayakorn, Wanwilai
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Vittayakorn, Naratip
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Maensiri, Santi
The sonochemical technique is a powerful synthetic method for the production of nanostructured inorganic powders. Monosized spherical barium zirconium titanate [Ba(Zr<inf>x</inf>Ti<inf>1-</inf><inf>x</inf>)O<inf>3</inf>; BZT], with x = 0.00, 0.05, 0.20 and 0.40 nanoparticles, were synthesized successfully through sonochemical reaction. The phase formation as well as crystal structure and morphology were investigated. The as-prepared powders were identified by X-ray diffraction (XRD). The cubic perovskite structure of BZT was formed completely in a short irradiation time without the calcination process. The lattice parameter (a) of the samples increased with increasing zirconium concentration. Furthermore, when the concentration of zirconium increased, the reaction time must be increased in order to obtain phase-pure perovskite. The BZT nanoparticles showed a monosized spherical shape that was different from that in other preparation methods. The morphology of the products was very close to spherical, with the particle size distribution being rather narrow.
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Dielectric properties and characterizations of binary Cu(2-x)MgxP2O7 pyrophosphates
(2016-01-02)
Baitahe, Rattanai
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Vittayakorn, Naratip
Samples of the binary metal pyrophosphate, Cu<inf>(2-x)</inf>Mg<inf>(x)</inf>P<inf>2</inf>O<inf>7</inf> (x = 0.00 - 2.00), were prepared via solid state reaction. Vibrational bands of [P<inf>2</inf>O<inf>7</inf>]4- anion which contains the O-P-O radical ([PO<inf>2</inf>]-) and the P-O-P bride ([OPO]-) and approximate M-O stretching were identified by Raman scattering. A strong P-O-P band was observed clearly in Raman spectra, which indicated the formation of solid solution.The purity of synthetic powders were characterized by X-ray diffraction (XRD).The XRD patterns indicated that all the samples exhibited a single monoclinic phase structure. The complete solid solutions in the Cu<inf>(2-x)</inf>Mg<inf>(x)</inf>P<inf>2</inf>O<inf>7</inf> (x = 0.00 - 2.00) system were obtained. The unit cell volume changed, due to the difference between the final product structure and Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>.X-ray absorption near the edge structure (XANES) technique was used to confirm oxidation state of copper in the Cu(2-x)Mg<inf>x</inf>P<inf>2</inf>O<inf>7</inf>.The relative permittivity and dielectric loss of the samples were measured. The bond length and bond angle were analyzed by EXAFS and Raman techniques. The relative permittivity was seen to maintain temperature by substituting Mg2+ with Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>. These results were used to explain the crystal structure of materials in order to change the bond which affects dielectric phenomena.
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Directed synthesis, growth process and optical properties of monodispersed CaWO4 microspheres via a sonochemical route
(2015-01-01)
Janbua, Jira
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Mayamae, Jitkasem
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Wirunchit, Supamas
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Baitahe, Rattanai
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Vittayakorn, Naratip
Monodispersed calcium tungstate (CaWO<inf>4</inf>) microspheres were synthesized successfully via a sonochemical process in deionized (DI) water. The functional group and phase formation analyses were carried out using Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. XRD revealed that all samples were of pure tetragonal scheelite structure. FT-IR and Raman analysis exhibited a W-O stretching peak of molecular [WO<inf>4</inf>]2-, which related to the scheelite structure. The effect of ultrasonic irradiation times in the sonochemical process was investigated briefly for 1, 5, 15 and 30 min. The shape of the particles was revealed as spherically monodispersed with narrow size distribution and uniform features at the ultrasonic time of 5 min. This study also found that the spherical surface was composed of tightly packed nanosphere subunits. A possible mechanism for the formation of CaWO<inf>4</inf> powders with a different ultrasonic time was discussed in detail. Optical properties showed blue light emission at a wavelength of around 420 nm and an optical energy gap (E<inf>g</inf>) value of 3.32-3.36 eV. This journal is
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Correlation between the chromaticity, dielectric properties and structure of the binary metal pyrophosphates, Cu(2-x)ZnxP2O7
(2015-01-01)
Baitahe, Rattanai
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Vittayakorn, Naratip
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Maensiri, Santi
The binary metal pyrophosphates, Cu<inf>(2-x)</inf>Zn<inf>x</inf>P<inf>2</inf>O<inf>7</inf>; x = 0.50-1.50, were synthesized via solid state reaction in order to obtain information on their solid solution phase formation. Characteristic peaks of the β-phase were detected under UV/Vis light emission in the range of 1200-1250 cm-1. The P<inf>2</inf>O<inf>7</inf>4- ion, analyzed through vibration, carried the O-P-O radical, P-O-P bridge, and approximate M-O bond stretching, and was identified using Raman and Fourier transform infrared (FT-IR) spectra. The corrected dielectric constant (ε<inf>r</inf>) of the samples showed a similar value when Cu2+ was replaced by Zn2+ in the Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf> structure. However, a slightly decreasing ε<inf>r</inf> could still be seen when the component x increased. The color of the samples with x = 0.00-1.50 exhibit a greenish hue, except for the composition with x = 2.00, which presents a colourless powder. The CIE chromaticity coordinates of Cu<inf>(2-x)</inf>Zn<inf>x</inf>P<inf>2</inf>O<inf>7</inf>; x = 0.50 to 1.50, shifted from (0.303, 0.366) to (0.292, 0.388), thus corresponding to a visible wavelength that shifted from about 506 to 512 nm, and 561 nm for x = 0.00. The phenomena of both dielectric and optical properties resulted from the changing crystal structure of the respective P<inf>2</inf>O<inf>7</inf>4- cluster and octahedral M-O<inf>6</inf> site. Investigation of the crystal structure was carried out by using Rietveld refinement analysis, with support from the extended X-ray absorption fine structure (EXAFS) fitting technique. Furthermore, this study revealed the relationships for binary metal pyrophosphates between their structure and dielectric properties, and the correlation between their structure and optical properties, which was confirmed by the reduction in chemical bonding, bond angle, number of clusters, and distortion of the octahedral MO<inf>6</inf>.
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Phase formation and evolution of Cu:Zn partials in binary metal pyrophosphates Cu(2-x)Zn(x)P2O7; X ≈ 1
(2014-11-20)
Baitahe, Rattanai
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Vittayakorn, Naratip
Binary metal pyrophosphate powders were prepared by the solid state reaction method and subsequently calcined at 400, 500, 600, 700, and 800 °C in order to study Cu:Zn partial evolution to the final CuZnP<inf>2</inf>O<inf>7</inf> product. Synchrotron X-ray absorption, X-ray diffraction, Raman, FT-IR spectroscopy, and thermogravimetric analysis were used in this investigation. Phase evolution of the reaction products was investigated systemically. The results showed that complicated mixtures contributed to the reaction of synthesis temperature. The reaction comprised 3CuO·2P<inf>2</inf>O<inf>5</inf>·0.3NH<inf>3</inf>·0.2H<inf>2</inf>O, Cu<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>, and Zn<inf>2</inf>P<inf>2</inf>O<inf>7</inf>·3H<inf>2</inf>O intermediates. Decreasing percentage of 3CuO·2P<inf>2</inf>O<inf>5</inf>·0.3NH<inf>3</inf>·0.2H<inf>2</inf>O intermediates was related directly to an increasing final product. Cu:Zn contents changed in Cu<inf>(2-x)</inf>Zn<inf>(x)</inf>P<inf>2</inf>O<inf>7</inf> in the temperature range of 400-600 °C, when x ≈ 1 clearly was related linearly to the reaction temperature. The final product was confirmed by EXAFS fitting spectra as solid solution between the Cu and Zn atom in the CuZnP<inf>2</inf>O<inf>7</inf> structure, and it indicated environment around metal atoms.
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Influence of Mn doping on the magnetic properties of CoFe2O 4
(2014-01-03)
Roongtao, Rachanusorn
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Baitahe, Rattanai
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Vittayakorn, Naratip
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Seeharaj, Panpailin
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Vittayakorn, Wanwilai C.
A series of CoFe<inf>2-x</inf>MnxO<inf>4</inf> ceramics were synthesized successfully by conventional solid state reaction. The X-ray diffraction analysis proved that all samples were found to have a cubic spinel structure. Diffractograms were used for Rietveld refinement to determine lattice parameters, of which lattice parameter increased with increasing Mn concentration. The microstructure of the samples was studied using scanning electron microscopy. The vibrating sample magnetometer measurements showed that the highest saturated magnetization of 118.11 emu/g and coercivity of 46.89 Oe were observed in CoFe<inf>1.85</inf>Mn<inf>0.15</inf>O<inf>4</inf> ceramic. Furthermore, X-ray absorption spectra of the samples were recorded to determine the Co, Fe and Mn valence states and their preferentially sites of the spinel structure. © 2014 Taylor and Francis Group, LLC.
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Structural and magnetic properties of Zn doped CoFe2O 4
(2013-12-01)
Roongtao, Rachanusorn
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Baitahe, Rattanai
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Vittayakorn, Naratip
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Klysubun, Wantana
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Vittayakorn, Wanwilai C.
Zinc doped cobalt ferrite powders were prepared by the solid state reaction method. The effect of zinc substitution on structure, morphology and magnetic properties was investigated. The X-ray analysis confirmed existence of the single phase cubic spinel structure, while Rietveld refinement data showed increasing of lattice parameters with zinc content. In addition, saturated magnetization increased with increasing zinc concentration and it was contained at maximum in CoFe<inf>1.9</inf>Zn0.<inf>1</inf>O<inf>4</inf> powders. However, the value of coercivity was decreased with zinc doped content. Furthermore, the oxidative states were characterized by X-ray absorption spectroscopy. The results confirm that the structure contained Co2+, Fe3+ and Zn2+ ions. © 2013 Copyright Taylor and Francis Group, LLC.
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Synthesis of monodispersed perovskite barium zirconate (BaZrO3) by the sonochemical method
(2013-01-01)
Charoonsuk, Piyanut
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Baitahe, Rattanai
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Vittayakorn, Wanwilai
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Atiwongsangthong, Narin
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Muanghua, Rangson
Barium zirconate (BaZrO<inf>3</inf>) was synthesized successfully by the sonochemical method. The monophase of BaZrO<inf>3</inf> was formed completely in short irradiation time without the calcination process. X-ray diffraction, Fourier transform and Raman spectroscopy were used to characterize formation of the perovskite BaZrO<inf>3</inf> phase, which occurs in a 60 minute single phase with a cubic crystal structure at room temperature. Therefore, sonochemical irradiation could accelerate the formation of BaZrO<inf>3</inf> particles significantly. Furthermore, scanning electron microscopy investigated the uniform shape and size. The size distribution became narrow with increasing time, as a function of irradiation. © 2013 Copyright Taylor and Francis Group, LLC.

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