Structural analysis of nonlinearities of Ca4ReO(BO3)(3) (Re = La, Nd, Sm, Gd, Er, Y)

From the chemical bond viewpoint, second-order nonlinear optical (NLO) tensor coefficients of the family of new oxoborates Ca4ReO(BO3)(3) (CReOB, Re = La, Nd, Sm, Gd, Er, and Y) have been theoretically predicted. The d(11) tensor coefficient of CReOB is predicted to be -11 d(36)(KDP), which is the largest d(ij) tensor that has been found in borate crystals. From the structural characteristic of CReOB, we find the isolated BO33- clusters play a dominant role in contributions to the total nonlinearity, and the largest d(11) tensor of CReOB-type crystals is also ascribed to these BO33- clusters. We also find the NLO property of this family does not change dramatically for different rare-earth elements. The details of the calculation of CGdOB only are presented.

Vibrational spectroscopy of the borate mineral gaudefroyite Ca4Mn3+3-x(BO3)3(CO3)(O,OH) from N’Chwaning II mine, Kalahari, Republic of South Africa

Gaudefroyite Ca4Mn3+3-x(BO3)3(CO3)(O,OH)3 is an unusual mineral containing both borate and carbonate groups and is found in the oxidation zones of manganese minerals, and it is black in color. Vibrational spectroscopy has been used to explore the molecular structure of gaudefroyite. Gaudefroyite crystals are short dipyramidal or prismatic with prominent pyramidal terminations, to 5 cm. Two very sharp Raman bands at 927 and 1076 cm-1are assigned to trigonal borate and carbonate respectively. Broad Raman bands at 1194, 1219 and 1281 cm-1 are attributed to BOH in-plane bending modes. Raman bands at 649 and 670 cm-1 are assigned to the bending modes of trigonal and tetrahedral boron. Infrared spectroscopy supports these band assignments. Raman bands in the OH stretching region are of a low intensity. The combination of Raman and infrared spectroscopy enables the assessment of the molecular structure of gaudefroyite to be made.

Synthesis, photoluminescence, thermoluminescence and dosimetry properties of novel phosphor KSr4(BO3)(3):Ce

Polycrystalline powder sample of KSr4(BO3)(3) was synthesized by high-temperature solid-state reaction. The influence of different rare earth dopants, i.e. Tb3+, TM3+ and Ce3+, on thermoluminescence (TL) of KSr4(BO3)(3) Phosphor was discussed. The TL, photoluminescence (PL) and some dosimetric properties of Ce3+-activated KSr4(BO3)(3) phosphor were studied. The effect of the concentration of Ce3+ on TL intensity was investigated and the result showed that the optimum Ce3+ concentration was 0.2 mol%. The TL kinetic parameters of KSr4(BO3)(3):0.002 Ce3+ phosphor were calculated by computer glow curve deconvolution (CGCD) method. Characteristic emission peaking at about 407 and 383 nm due to the 4f(0)5d(1) -> F-2((5/2),(7/2)) transitions of Ce3+ ion were observed both in PL and three-dimensional (3D) TL spectra. The dose-response of KSr4(BO3)(3):0.002 Ce3+ to gamma-ray was linear in the range from 1 to 1000 mGy. In addition, the decay of the TL intensity of KSr4(BO3)(3):0.002 Ce3+ was also investigated.

Thermoluminescence characteristics of NaSr4(BO3)(3):Ce3+ under beta-ray irradiation

The thermoluminescence (TL) properties of Ce3+ doped NaSr4(BO3)(3) phosphor under the beta-ray irradiation were reported. The polycrystalline sample was synthesized by high temperature solid-state reaction. The TL glow curve of NaSr4(BO3)(3):Ce3+ phosphor was composed of only one peak. TL kinetic parameters of NaSr4(BO3)(3):Ce3+ were deduced by the peak shape method, the activation energy (E) was 0.590 eV and the frequency factor was 1.008x10(6) s(-1). TL dose response was linear in the range of measurement. The 3-dimensional (3D) TL emission spectrum was also recorded, the emission spectrum consisted of two bands located at 441 and 479 nm respectively, corresponding to the characteristic 4f(0)5d(1)-> F-2((5/2,7/2)) transitions of the Ce3+ ion. The fading behavior of the NaSr4(BO3)(3):Ce3+ phosphor over a period of 15 d was also studied.

Thermoluminescence properties of Ce3+-doped LiSr4(BO3)(3) phosphor

Borates LiSr4(BO3)(3) were synthesized by high-temperature solid-state reaction. The thermoluminescence (TL) and some of the dosimetric characteristics of Ce3+-activated LiSr4(BO3)(3) were reported. The TL glow curve is composed of only one peak located at about 209 degrees C between room temperature and 500 degrees C. The Optimum Ce3+ concentration is 1 mol% to obtain the highest TL intensity. The TL kinetic parameters of LiSr4(BO3)(3):0.01Ce(3+) were studied by the peak shape method. The TL dose response is linear in the protection dose ranging from 1 mGy to 1 Gy. The three-dimensional thermoluminescence emission spectra were also studied, peaking at 441 and 474 nm due to the characteristic transition of Ce3+.

VIV-UV excited luminescent properties of LnCa4O(BO3)3 : RE3+(Ln = Y, La, Gd; Re=Eu, Tb, Dy, Ce)

Calcium lanthanide oxyborate doped with rare-earth ions LnCa(4)O(BO3)(3):RE3+ (LnCOB:RE, Ln = Y, La, Gd, RE = Eu, Tb, Dy, Cc) was synthesized by the method of solid-state reaction at high temperature. Their fluorescent spectra were measured from vacuum ultraviolet (VUV) to visible region at room temperature. Their excitation spectra all have a broadband center at about 188 nm, which is ascribed to host absorption. Using Dorenbos' and J phi rgensen's work [P. Dorenbos, J. Lumin. 91 (2000) 91, R. Resfeld, C.K. J phi rgensen. Lasers and Excite States of Rare Earth [M], Springer, Berlin, 1977, p. 45], the position of the lowest 5d levels E(Ln,A) and charge transfer band E-ct were calculated and compared with their excitation spectra.Eu3+ and Tb3+ ions doped into LnCOB show efficient luminescence under VUV and UV irradiation. In this system, Ce3+ ions do not show efficient luminescence and quench the luminescence of Tb3+ ions when Tb3+ and Ce3+ ions are co-doped into LnCOB. GdCOB doped with Dy3+ shows yellowish white light under irradiation of 254 nm light for the reason that Gd ions transfer the energy from itself to Dy.

Investigation on relationship between charge transfer position and dielectric definition of average energy gap in Eu3+-doped compounds

The dielectric definition of average energy gap E-g of the chemical bond has been calculated quantitatively in Eu3+-doped 30 lanthanide compounds based on the dielectric theory of chemical bond for complex structure crystals. The relationship between the experimental charge transfer (CT) energy of Eu3+ and the corresponding average energy gap E-g has been studied. The results show that the CT energy increases linearly with increasing of the average energy gap E-g. The linear model is obtained. It allows us to predict the CT position of Eu3+-doped lanthanide compounds with knowledge of the crystal structure and index of refraction. Applied to the Ca4GdO(BO3)(3):Eu and Li2Lu5O4(BO3)(3):Eu crystals, the predicted results of CT energies are in good agreement with the experimental values, and it can be concluded that the lowest CT energy in Li2Lu5O4(BO3)(3):Eu originates from the site of Lu1.

Nonlinear refractive index of RECOB (RE = Gd and La) crystals

The Z-scan technique is employed to obtain the nonlinear refractive index (n (2)) of the Ca(4)REO(BO(3))(3) (RECOB, where RE = Gd and La) single crystals using 30 fs laser pulses centered at 780 nm for the two orthogonal orientations determined by the optical axes (X and Z) relative to the direction of propagation of the laser beam (k//Y// crystallographic b-axis). The large values of n (2) indicate that both GdCOB and LaCOB are potential hosts for Yb:RECOB lasers operating in the Kerr-lens mode locking (KLM) regime.

稀土离子的电荷迁移带与化学键性质研究

本论文主要研究的是掺杂在无机材料中的稀土离子的电荷迁移带，利用复杂晶体化学键的介电理论对晶体的化学键性质进行计算和分析，阐明了稀土离子的电荷迁移带与基质的化学键性质之间的规律，揭示了宏观电荷迁移带的微观机制，进而丰富和发展了稀土发光材料的理论知识。 根据大量掺杂稀土离子的化合物的电荷迁移带数据，利用复杂晶体的介电理论计算和分析出化合物的共价性、键体积极化率、配体在晶体中所呈现的电荷及配位数，进而得到由这四个参数定义的环境因子he。发现环境因子he能够有效地描述电荷迁移带的变化趋势,可以揭示电荷迁移的微观机制。具体获得了Eu3+、Sm3+和Yb3+在不同基质中的电荷迁移能与环境因子之间的定量关系。通过这些定量关系式，我们能够利用复杂晶体的介电理论来估算各种复杂晶体中稀土离子的电荷迁移带位置，为电荷迁移带方面的研究工作提供了理论依据。反过来，利用这一关系我们也可以从实验上测得的电荷迁移能数据来判断晶体结构的正确性。在此基础上，我们从化学键和YBO3：Eu的电荷迁移带的角度出发，研究了YBO3的结构，从而确定它的空间群为C2/c，排除了其他的可能性。 考虑到Eu3+的电荷迁移能随着基质平均能隙的增大而增大，而且利用复杂晶体化学键的介电理论可以估算化学键的平均能隙，我们研究了Eu3+在不同基质中的电荷迁移能与相应的化学键的平均能隙之间的关系，发现它们之间符合定量的线性关系。通过这一线性关系估算出的电荷迁移能与实验值一致，说明利用化学键的平均能隙来估算电荷迁移能的可靠性。在此基础上，我们预测了发光材料Gd4GdO(BO3)3:Eu的电荷迁移带位置，计算的结果与实验值相吻合；探索复杂化合物Li2Lu5O4(BO3)3:Eu中Eu3+取代的阳离子的格位，计算结果表明能量最低的电荷迁移带来源于Eu3+取代五种Lu中的Lu1格位，电荷迁移能的计算值与实验值一致。块状和纳米的Sr2CeO4分别通过高温固相法和溶胶凝胶法获得，根据电荷迁移能随平均能隙的增大而增大的规律，可以将激发光谱中出现的三个峰分别归属为：能量最高的激发峰来源于从O1到Ce的电荷迁移，能量最低的激发峰来源于从O2到Ce的电荷迁移，中间的峰是前面两种峰的叠加。

A Mineralogical Study of a Dravitic Tourmaline from the Grenville Province

Tourmaline from a gem-quality deposit in the Grenville province has been studied with X-ray diffraction, visible-near infrared spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, electron microprobe and optical measurements. The tourmaline is found within tremolite-rich calc-silicate pods hosted in marble of the Central Metasedimentary Belt. The crystals are greenish-greyish-brown and have yielded facetable material up to 2.09 carats in size. Using the classification of Henry et al. 2011 the tourmaline is classified as a dravite, with a representative formula shown to be (Na0.73Ca0.2380.032)(Mg2+2.913Fe2+0.057Ti4+0.030) (Al3+5.787Fe3+0.017Mg2+0.14)(Si6.013O18)(BO3)3(OH)3((OH,O)0.907F0.093). Rietveld analysis of powder diffraction data gives a = 15.9436(8) Å, c = 7.2126(7) Å and a unit cell volume of 1587.8 Å3. A polished thin section was cut perpendicular to the c-axis of one tourmaline crystal, which showed zoning from a dark brown core into a lighter rim into a thin darker rim and back into lighter zonation. Through the geochemical data, three key stages of crystal growth can be seen within this thin section. The first is the core stage which occurs from the dark core to the first colourless zone; the second is from this colourless zone increasing in brown colour to the outer limit before a sudden absence of colour is noted; the third is a sharp change from the end of the second and is entirely colourless. These events are the result of metamorphism and hydrothermal fluids resulting from nearby felsic intrusive plutons. Scanning electron microscope, and electron microprobe traverses across this cross-section revealed that the green colour is the result of iron present throughout the system while the brown colour is correlated with titanium content. Crystal inclusions in the tourmaline of chlorapatite, and zircon were identified by petrographic analysis and confirmed using scanning electron microscope data and occur within the third stage of formation.

A Mineralogical Study of a Dravitic Tourmaline from the Grenville Province

Tourmaline from a gem-quality deposit in the Grenville province has been studied with X-ray diffraction, visible-near infrared spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, electron microprobe and optical measurements. The tourmaline is found within tremolite-rich calc-silicate pods hosted in marble of the Central Metasedimentary Belt. The crystals are greenish-greyish-brown and have yielded facetable material up to 2.09 carats in size. Using the classification of Henry et al. 2011 the tourmaline is classified as a dravite, with a representative formula shown to be (Na0.73Ca0.2380.032)(Mg2+2.913Fe2+0.057Ti4+0.030) (Al3+5.787Fe3+0.017Mg2+0.14)(Si6.013O18)(BO3)3(OH)3((OH,O)0.907F0.093). Rietveld analysis of powder diffraction data gives a = 15.9436(8) Å, c = 7.2126(7) Å and a unit cell volume of 1587.8 Å3. A polished thin section was cut perpendicular to the c-axis of one tourmaline crystal, which showed zoning from a dark brown core into a lighter rim into a thin darker rim and back into lighter zonation. Through the geochemical data, three key stages of crystal growth can be seen within this thin section. The first is the core stage which occurs from the dark core to the first colourless zone; the second is from this colourless zone increasing in brown colour to the outer limit before a sudden absence of colour is noted; the third is a sharp change from the end of the second and is entirely colourless. These events are the result of metamorphism and hydrothermal fluids resulting from nearby felsic intrusive plutons. Scanning electron microscope, and electron microprobe traverses across this cross-section revealed that the green colour is the result of iron present throughout the system while the brown colour is correlated with titanium content. Crystal inclusions in the tourmaline of chlorapatite, and zircon were identified by petrographic analysis and confirmed using scanning electron microscope data and occur within the third stage of formation.

The borate mineral jeremejevite Al6(BO3)5(F,OH)3 – A vibrational spectroscopic study

Jeremejevite is a borate mineral of aluminium and is of variable colour, making the mineral and important inexpensive jewel. The mineral contains variable amounts of F and OH, depending on origin. A comparison of the vibrational spectroscopic data is made with the published data of borate minerals. Raman spectra were averaged over a range of crystal orientations. Two intense Raman bands observed at 961 and 1067 cm−1 are assigned to the symmetric stretching and antisymmetric stretching modes of trigonal boron. Infrared spectrum, bands observed at 1229, 1304, 1350, 1388 and 1448 cm−1 are attributed to BOH in-plane bending modes. Intense Raman band found at 372 cm−1 with other bands of significant intensity at 327 and 417 cm−1 is assigned to trigonal borate bending modes. A quite intense Raman band is found at 3673 cm−1 with other sharp Raman bands found at 3521, 3625 and 3703 cm−1 are assigned to the stretching modes of OH. Raman and infrared spectroscopy has been used to assess the molecular structure of the mineral jeremejevite. Such research is important in the study of borate based nanomaterials.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor(单掺杂与共掺杂离子对Sr_2Mg(BO_3)_2磷光体热释发光的影响)

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.

Luminescence properties of Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors prepared by spray pyrolysis process

Starting from metal nitrate aqueous solutions and H3BO3, Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors were synthesized by spray pyrolysis followed by annealing at high temperature. The obtained phosphor particles have spherical morphology with size in the range 0.5-2 mu m. Independent of the x values in Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors, the Eu3+ ion shows its characteristic D-5(0), (1)-F-7(J) (J = 0, 1, 2, 3, 4) transitions with D-5(0)-F-7(2) red emission (612 nm) as the most prominent group. The photoluminescence intensity of phosphors increases with the increase of x value in Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) due to an energy migration process like Gd3+-(Gd3+)(n)-Eu3+ that occurred in the host materials.