β-Ga_(2)O_(3):Cr single crystals were grown by floating zone technique.Absorption spectra and fluorescence spectra were measured at room temperature.The values of field splitting parameter Dq and Racah parameter B we...β-Ga_(2)O_(3):Cr single crystals were grown by floating zone technique.Absorption spectra and fluorescence spectra were measured at room temperature.The values of field splitting parameter Dq and Racah parameter B were obtained by the peak values of absorption spectra.The value 10Dq/B=23.14 manifests that inβ-Ga2O3 crystals Cr3+ions are influenced by low energy crystal field.After high temperature annealing in air,the Cr3+intrinsic emission was enhanced and the green lumines-cence disappeared.The strong and broad 691 nm emission was obtained at 420 nm excitation due to the electron transition occurred from 4T2 to 4A2.The studies manifest that theβ-Ga2O3 crystals have the potential application for tunable laser.展开更多
Optical floating zone（FZ） crystal growth involving growth stability and as-grown crystal perfection is affected by experimental conditions and the specific material. Referring to rare earth silicides, high purity of...Optical floating zone（FZ） crystal growth involving growth stability and as-grown crystal perfection is affected by experimental conditions and the specific material. Referring to rare earth silicides, high purity of raw rare earth elements and ambient argon atmosphere are crucial to grow high-quality crystals; the maximum zone height is determined by equating the capillary forces of the surface tension; and asymmetric counter rotation of crystal and feed rod with convex（toward the melt） interfaces are favored to reach single crystals. Influences of several other growth parameters were also discussed in detail in this paper.展开更多
Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structur...Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structure of the grown crystals is analyzed by powder X-ray diffraction and scanning electron microscopy.The defects in the as-grown crystals, including low-angle grain boundary and inclusions are studied. An off-stoichiometric phenomenon is found with a slight Cr deficiency in different parts. The relationship between defects and growth conditions during crystal growth is also discussed. The magnetic properties show spin-glass phase features with weak ferromagnetic behavior below 30 K.展开更多
Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3（R=Pr,Tb and Gd） single crystals due to its containerless melting and high stability of the floating zone.One serious prob...Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3（R=Pr,Tb and Gd） single crystals due to its containerless melting and high stability of the floating zone.One serious problem during the single crystal growth,precipitates of secondary phases,was discussed from the following four parts：precipitates from the raw materials and preparation process,precipitates formed during the growing process,precipitates in the melts and precipitates in the grown crystals.Annealing treatment and composition shift can effectively reduce the precipitates which are not formed during the crystallization but precipitated on post-solidification cooling from the as-grown crystal matrix because of the retrograde solubility of Si.展开更多
Gd2PdSi3 single crystals were grown by a vertical floating zone method with radiation heating at a zone traveling rate of 3 mm/h. The compound exhibited congruent melting behavior at a liquidus temperature of about 17...Gd2PdSi3 single crystals were grown by a vertical floating zone method with radiation heating at a zone traveling rate of 3 mm/h. The compound exhibited congruent melting behavior at a liquidus temperature of about 1700 ＆#176;C. The slightly Pd-depleted composition of the crystal, with respect to the nominal Gd2PdSi3 stoichiometry, led to gradual accumulation of Pd in the traveling zone and to a decreasing operating temperature during the growth process. Thin platelet-like precipitates of a GdSi phase were detected in the stoichiometric feed rod growth crystal matrix which can be reduced by annealing treatment. Feed rod composition shift crystal growth was proved to be a better way of getting high quality of Gd2PdSi3 single crystal.展开更多
基金the National Natural Science Foundation of China(Grant Nos.50472032 and 50672105)the Hundred Talents Program of the Chinese Academy of Sciences
文摘β-Ga_(2)O_(3):Cr single crystals were grown by floating zone technique.Absorption spectra and fluorescence spectra were measured at room temperature.The values of field splitting parameter Dq and Racah parameter B were obtained by the peak values of absorption spectra.The value 10Dq/B=23.14 manifests that inβ-Ga2O3 crystals Cr3+ions are influenced by low energy crystal field.After high temperature annealing in air,the Cr3+intrinsic emission was enhanced and the green lumines-cence disappeared.The strong and broad 691 nm emission was obtained at 420 nm excitation due to the electron transition occurred from 4T2 to 4A2.The studies manifest that theβ-Ga2O3 crystals have the potential application for tunable laser.
基金financially supported by the National Natural Science Foundation of China (No. 51301021)Special Fund for Basic Scientific Research of Central Colleges (No. 2013G1311051)the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University (No. SKLSP201302)
文摘Optical floating zone（FZ） crystal growth involving growth stability and as-grown crystal perfection is affected by experimental conditions and the specific material. Referring to rare earth silicides, high purity of raw rare earth elements and ambient argon atmosphere are crucial to grow high-quality crystals; the maximum zone height is determined by equating the capillary forces of the surface tension; and asymmetric counter rotation of crystal and feed rod with convex（toward the melt） interfaces are favored to reach single crystals. Influences of several other growth parameters were also discussed in detail in this paper.
基金financial support of the National Natural Science Foundation of China (Nos. 51471135 and 51301133)the National Key Research and Development Program (No. 2016YFB1100101)Shaanxi International Cooperation Program
文摘Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structure of the grown crystals is analyzed by powder X-ray diffraction and scanning electron microscopy.The defects in the as-grown crystals, including low-angle grain boundary and inclusions are studied. An off-stoichiometric phenomenon is found with a slight Cr deficiency in different parts. The relationship between defects and growth conditions during crystal growth is also discussed. The magnetic properties show spin-glass phase features with weak ferromagnetic behavior below 30 K.
基金Project (2008629045) supported by the China Scholarship Council (Constructing High-Level University Project)
文摘Floating zone method with optical radiation heating was applied to growing a class of R2PdSi3（R=Pr,Tb and Gd） single crystals due to its containerless melting and high stability of the floating zone.One serious problem during the single crystal growth,precipitates of secondary phases,was discussed from the following four parts：precipitates from the raw materials and preparation process,precipitates formed during the growing process,precipitates in the melts and precipitates in the grown crystals.Annealing treatment and composition shift can effectively reduce the precipitates which are not formed during the crystallization but precipitated on post-solidification cooling from the as-grown crystal matrix because of the retrograde solubility of Si.
基金Project(51301021)supported by the National Natural Science Foundation of ChinaProjects(2013G1311051,CHD2011JC139)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(SKLSP201302)supported by the State Key Laboratory of Solidification Processing in NWPU,China
文摘Gd2PdSi3 single crystals were grown by a vertical floating zone method with radiation heating at a zone traveling rate of 3 mm/h. The compound exhibited congruent melting behavior at a liquidus temperature of about 1700 ＆#176;C. The slightly Pd-depleted composition of the crystal, with respect to the nominal Gd2PdSi3 stoichiometry, led to gradual accumulation of Pd in the traveling zone and to a decreasing operating temperature during the growth process. Thin platelet-like precipitates of a GdSi phase were detected in the stoichiometric feed rod growth crystal matrix which can be reduced by annealing treatment. Feed rod composition shift crystal growth was proved to be a better way of getting high quality of Gd2PdSi3 single crystal.
