The tetragonal crystalline form of boron nitride remains in theoretical prediction stage till date without being synthesized in real practice and in accordance; properties could not be verified experimentally. Here we synthesize tetragonal boron nitride through a low-cost chemical synthesis route for the first time along with thermodynamic analysis and identification of evolved product gases through gas chromatography to authenticate the chemical reaction feasibility. The evolution of tetragonal boron nitride is substantiated with XRD analysis, Raman spectroscopy, x-ray photoelectron spectroscopy and FEG-TEM based SADP and EDS analysis together with IFFT micrograph-based measurement of the interplanar spacing of dominating (110) growth plane. The experimentally measured lattice parameters (a = 0.4378 nm, c = 0.2541 nm) closely match with those predicted theoretically (a = 0.4380 nm, c = 0.2540 nm). The presence of sp³ bonding in synthesized material is also confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy. Furthermore, we determine some significant properties of synthesized tetragonal boron nitride that envisage large optical band gap (5.66 eV), low electrical conductivity (671 S m⁻¹) of semiconducting range, low density (1.83 g cm⁻³), high hardness (28 GPa) and the highest specific hardness (15.30 GPa/g cm⁻³) among other forms of polycrystalline boron nitride and commonly used hard ceramic materials. Accordingly, a new dimension is hereby added to material development for electronic/optoelectronic applications as well as in low-density hard structural material synthesis in view of using tetragonal boron nitride as reinforcement for metal matrix composites.

氮化硼的四方晶型一直保留到理论预测阶段，直到今天仍未在实际实践中合成。属性无法通过实验进行验证。在这里，我们首次通过低成本的化学合成路线合成了四方氮化硼，并进行了热力学分析和通过气相色谱法鉴定生成的产物气体，从而验证了化学反应的可行性。借助XRD分析，拉曼光谱，X射线光电子能谱和基于FEG-TEM的SADP和EDS分析以及基于IFFT显微照片的主要（110）生长平面间距的测量，可以证实四方氮化硼的演变。实验测得的晶格参数（a  = 0.4378 nm，c  = 0.2541 nm）与理论上预测的值（a  = 0.4380 nm，c  = 0.2540 nm）紧密匹配。合成材料中sp ³键的存在也通过拉曼光谱和X射线光电子能谱确认。此外，我们确定了合成四方氮化硼的一些重要性能，这些性能包括大的光学带隙（5.66 eV），半导体范围的低电导率（671 S m ^-1），低密度（1.83 g cm ^-3），高硬度（ 28 GPa）和最高比硬度（15.30 GPa / g cm ^-3）以及其他形式的多晶氮化硼和常用的硬质陶瓷材料。因此，鉴于将四方氮化硼用作金属基复合材料的增强材料，因此在电子/光电应用以及低密度硬质结构材料合成中的材料开发中增加了新的维度。