The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results...The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4.6Na2MoO4 did not exist; however, it confirmed the existence of the compound Li2MoO4.3Na2MoO4 in the Li2MoO4-Na2MoO4 systen＇ls. With regard to the system of Na2MoO4-K2MoO4, we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1：1 and 1：2 intermediate compounds, refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams.展开更多
The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results...The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4·6Na2MoO4 did not exist; however,it confirmed the existence of the compound Li2MoO4·3Na2MoO4 in the Li2MoO4-Na2MoO4 systems. With regard to the system of Na2MoO4-K2MoO4,we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1∶1 and 1∶2 intermediate compounds,refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams.展开更多
K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultravi...K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet （394 nm） and blue （465 nm） light, and emitted red light at 616 nm. The influence of Eu3＋concentration, sintering temperature and charge compensators （K＋, Na＋ or Li＋ ） on the emission intensity were investigated. The results indicated that concentration quenching of Eu3＋ was not observed within 30mol.% Eu 3＋, 600 oC was a suitable sintering temperature for preparation of K2 Ba（MoO4）2：Eu3＋phosphors, and K＋ ions gave the best improvement to enhance the emission intensity. The CIE chromaticity coordinates of K2 Ba（MoO4）2：0.05Eu3＋phosphor were calculated to be （0.68, 0.32）, and color purity was 97.4%.展开更多
Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calcula...Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No.20373040).
文摘The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4.6Na2MoO4 did not exist; however, it confirmed the existence of the compound Li2MoO4.3Na2MoO4 in the Li2MoO4-Na2MoO4 systen＇ls. With regard to the system of Na2MoO4-K2MoO4, we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1：1 and 1：2 intermediate compounds, refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams.
文摘The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4·6Na2MoO4 did not exist; however,it confirmed the existence of the compound Li2MoO4·3Na2MoO4 in the Li2MoO4-Na2MoO4 systems. With regard to the system of Na2MoO4-K2MoO4,we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1∶1 and 1∶2 intermediate compounds,refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams.
基金Project supported by Natural Science Foundation of Fujian Province (2011J033)
文摘K2Ba（MoO4）2：Eu3＋ phosphors were synthesized by solid-state reaction. The emission and excitation spectra of K2 Ba（MoO4）2：Eu3＋ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet （394 nm） and blue （465 nm） light, and emitted red light at 616 nm. The influence of Eu3＋concentration, sintering temperature and charge compensators （K＋, Na＋ or Li＋ ） on the emission intensity were investigated. The results indicated that concentration quenching of Eu3＋ was not observed within 30mol.% Eu 3＋, 600 oC was a suitable sintering temperature for preparation of K2 Ba（MoO4）2：Eu3＋phosphors, and K＋ ions gave the best improvement to enhance the emission intensity. The CIE chromaticity coordinates of K2 Ba（MoO4）2：0.05Eu3＋phosphor were calculated to be （0.68, 0.32）, and color purity was 97.4%.
基金Project supported by the Natural Science Foundation of Anhui Province,China(Grant Nos.KJ2018A0588 and KJ2017A625)
文摘Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.
