Synthesis, Growth, and Characterization of a New Semiorganic Nonlinear Optical Crystal: l-Alanine Sodium Nitrate (LASN)

Abstract

A new semiorganic material of L-alanine sodium nitrate (LASN) has been synthesized and successfully grown by the slow evaporation solution growth method. The grown crystals have been subjected to various characterization techniques such as single crystal X-ray diffraction studies, FT-IR and laser Raman analyses to determine the crystal structure and functional groups, respectively. Crystalline perfection of the grown crystal was analyzed by the high resolution X-ray diffraction technique (HRXRD). Mechanical behavior of the grown LASN crystal was analyzed by Vicker's microhardness test. Thermogravimetric and differential thermal analyses of the grown crystal revealed that there is no phase transformation in LASN, and its thermal stability was found to be good. The dielectric measurement was made as function of frequency (range 0.2-200 kHz). The growth feature of the LASN crystal was studied by wet chemical etching studies. Lower cutoff wavelength and optical transmission window of LASN crystal was found by UV-vis-NIR studies. Laser damage threshold value was determined to be 15.6 and 11.4 GW/cm 2 , respectively, for single shot and multiple shots, by using 5 ns laser pulses at a 10 Hz repetition rate from a Q-switched Nd:YAG laser with a wavelength of 1064 nm. Second harmonic generation efficiency was determined and is about two times that of KDP crystal.

Comments on papers reporting IR‐spectra and other data of alleged L‐alanine alaninium nitrate and L‐alanine sodium nitrate crystals

“…In [12] a correct IRspectrum of (A) is given (Fig. 1d), supporting the data of [9] and proving the falsity in [8] and [10]. In their other paper [13], grown crystals of (A·HA·NO 3 ) were presented and characterized by powder X-ray diffraction, their IR-spectrum, thermal properties, etc.…”

“…Table 1 Unit cell parameters and space groups reported for (A), (A·HA·NO 3 ) and "(A·NaNO 3 )". These data also suggest that the species presented in [10] is in fact not (A·NaNO 3 ) but (A). Also note the fact that the values given in [6] and [8] correspond perfectly in every decimal -except that in [8] no value for β is given, although the structure is reported to be monoclinic.…”

“…To sum up, we believe to have shown that there are some data given for crystals supposed to be (A·HA·NO 3 ) [6,8] or (A·NaNO 3 ) [10] which obviously were obtained by investigating pure (A). Furthermore, there is some doubt on the reliability of the measurements when data from different publications (and once -even worsereferring to different compounds!)…”

“…Sadly, this is no exclusive mistake. In another paper, a novel Alanine compound is reported, namely Lalanine sodium nitrate, (A·NaNO 3 ) [10]. The IR-spectrum of "(A·NaNO 3 )" given in that paper in fact represents one of (A) (Fig.…”

“…The dubiousness of these results is amplified by the fact that the authors reported that X-ray diffraction experiments had been performed, but neglected to report (or probably even perform) any sound single crystal analysis to prove the structure. This is not only true for [10] but also for [6]. In both studies it is explicitly stated that single crystal analysis has been performed (barring results, however).…”