Borates crystallization

A number of inorganic materials, e.g., KDP, KTP, LiNb03, LiI03, and borate crystals (2), are readily available on the market for parametric effects. However, these materials are very difficult to fabricate and are not easily integrated with semiconductor materials into monolithic circuits. 

This review gives a brief presentation of the basic concepts and calculation methods of the "anionic group theory" for the NLO effect in borate crystals. On this basis, boron-oxygen groups of various known borate structure types have been classified and systematic calculations were carried out for microscopic second-order susceptibilities of the groups. 

In the following part we will give a brief description of the "anionic group theory" for the NLO effects in crystals, including the basic concepts and calculation methods adopted. In the next section we will discuss how to use this theoretical model to develop new UV NLO crystals in the borate series. Finally, the measurements and characteristic features of the NLO properties of these new borate crystals will be discussed. 

We now proceed to apply our anionic group theory to a systematic discussion of the NLO effects in borate crystals. The extension of our investigation into the NLO effects of borate crystals has great practical significance in two respects. On the one hand, most borate crystals are transparent far into the intermediate UV region and occasionally even farther because of the large difference in the electro-... 

III. Measurements and calculations of the SHG coefficients for BBO, LBO and another borate crystals. 

Fig. 12. Experimental setup for the frequency comparison between the IS — 3S and 2S — 6S/D transitions (TiSa titanium sapphire laser, LBO lithium tri-borate crystal, BBO /3-barium borate crystal)...

Figure 5 Schematic diagram of an experimental set-up for the state-selective study of laser-induced desorption. KDP potassium dideuterium phosphate crystal, BBO p-barium borate crystal, MCP microchannel plate [11].

Figure 6 Block diagram of the two-color optical parametric amplifier (OPA) and IR-Raman apparatus. CPA = Chirped pulse amplification system Fs OSC = femtosecond Ti sapphire oscillator Stretch = pulse stretcher Regen = regenerative pulse amplifier SHGYAG = intracavity frequency-doubled Q-switched Nd YAG laser YAG = diode-pumped, single longitudinal mode, Q-switched Nd YAG laser KTA = potassium titanyl arsenate crystals BBO = /J-barium borate crystal PMT = photomultiplier tube HNF = holographic notch filter IF = narrow-band interference filter CCD = charge-coupled device optical array detector. (From Ref. 96.)...

Borate minerals are common but synthesized examples are relatively rare [11]. We also notice that the borate crystals were usually grown by high temperature methods, exemplified by the high temperature flux and melt techniques [12-14]. There were a few reports on the preparation of borates by using the sol-gel technique. 

Xue D., Betzler K., Hesse H. and hammers D., Nonlinear optical properties of borate crystals. Solid State Commm., 114 (2000) pp. 21-25. 

A major problem which awaits clarification concerns the detailed nature of the borate crystal growth processes from the melts and fluxed melts. From this point of view, it... 

There were some attempts to estimate acid-base properties for oxide compounds, both solids and melts. The most popular of them is Lux-Flood s acid-base theory.2,3 This concept seems to be more effective for estimating the acid-base characteristics of anhydrous borates and of some promising solvents for the flux growth of borate crystals. According to Lewis-Lux s equation,... 

Borax is also manufactured from calcium borates by heating with a sodium carbonate/sodium hydrogen carbonate/sodium hydroxide solution, whereupon the calcium carbonate precipitates out and sodium borate crystallizes out. Anhydrous borax is formed by calcining water-containing sodium borates initially in rotary tube furnaces, then in standing furnaces, it being produced as a liquid which is poured e.g. into molds. 

Assignments of some vibrational modes of B03- in an indium borate crystal have been attempted, together with some for lattice modes.199... 

Nonlinear crystals are normally used for frequency doubling and mixing down to 200 nm, where the oxygen bands in air start to absorb. The p-barium borate crystal has a 189 nm cut-off, which is determined by the absorption in the crystal itself. Practically it is used down to about 200 nm, where the radiation is absorbed by oxygen in air. For shorter wavelengths the oxygen has to be removed from the path of the laser radiation. 

LijNaBFg doped with Cu and co-doped with P are synthesized by a wet chemical technique and exposed to gamma-rays of Co for their TL properties. The XRD technique shows the crystalline nature of the prepared material. The crystalline form of the materials is characterized by a powder XRD pattern recorded on a Philips P Analytical X Pert Pro diffractometer at room temperature. The XRD pattern of Li2NaBFg is shown in Figure 7.38. This material produced well-defined XRD lines for the powder samples that confirm its crystalline nature. However, for recorded XRD patterns, no matching files are seen in the JCPDS library (limited numbers of files are only available for mixed lithium magnesium borate crystals). The XRD pattern of LijNaBF material did not indicate individual presence of any traces of ammonium fluoride and other likely phases, which is an indirect evidence for the formation of the desired compound. The final product was formed in homogeneous white powder form. 

FIGURE 22.14 (a) Schematic representation diagram of the three-beam PM technique that shows two excitation pulses, and one probe pulse and the associated optical transitions induced in the polymer film, (b) Schematic representation diagram of the three-beam experimental setup. Ti S are Ti sapphire lasers OPO is an optical parametric oscillator BBO is barium borate crystal doubler and AOM is acousto-optic modulator. (From Frolov, S.V., et al., Phys. Rev. B, 65, 205209, 2002. With permission.)... 

Figures 2 and 3 show how the appearance of the residuals and autocorrelation function for a pulsed excitation experiment typically depend on the appropriateness of the fitting function. In panel A of both figures, L shows an actual excitation pulse profile (more properly, the instrument response function) that was generated by an argon ion laser that pumped a dye laser circulating rhodamine 6G, the tuned output of which was frequency-doubled to 295 nm (nanometer = 10" m = 10 A) by passage through a p-barium borate crystal (cf.

II. Lueneburgite—300°C endotherm, luene-burgiteis dehydrates and is transformed to phosphate and borate 645 °C exotherm, phosphate crystallizes 770 °C exotherm, borate crystallizes. 

---