• Nuclear Engineering and Technology
• /
• v.54 no.9
• /
• pp.3580-3585
• /
• 2022

The thermal stability of carbohydrazide, hydrazine nitrate, acetohydroxamic acid in nitric acid solutions has been studied at atmospheric pressure and above atmospheric pressure. The volumes of gaseous products of thermolysis and the maximum rate of gas evolution have been determined at atmospheric pressure. It has been shown that, despite the high rate of gas evolution and large volumes of evolved gases, the conditions for the development of autocatalytic oxidation are not created. Exothermic processes are observed in a closed vessel in the temperature range of 50-250 ℃. With an increase in the concentration of nitric acid, the temperatures of the onset of exothermic effects for all mixtures decrease, and the values of the total thermal effects of reactions increase, to the greatest extent for solutions with carbohydrazide.

• Transactions on Electrical and Electronic Materials
• /
• v.4 no.5
• /
• pp.28-32
• /
• 2003

Europium-doped gadolinium oxide ($Gd_2O_3;Eu^{3+}$) phosphors have been prepared by combustion method using urea[H$_2$NCONH$_2$] or carbohydrazide[H$_2$NNHCONHNH$_2$] as fuel materials in a preheated furnace at 500$^{\circ}C$. The phosphors obtained were fired at 1200$^{\circ}C$ for 3 hours to get better luminescent properties. The combustion method used was found to be a simple and fast method for the preparation of fine-sized particles. The influence of the fuel/oxidant (urea or carbohydrazide/nitrate) mole ratio on the phosphor has been investigated and the optimum values for various parameters have been determined. By this method, phosphor that has better brightness and smaller size particles than that obtained by conventional method has been prepared.d has been prepared.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.1009-1012
• /
• 2003

A novel powder processing technique for the preparation of copper activated zinc sulfide (ZnS:Cu,Al) phosphor by combustion process has been proposed. Exothermic reaction between dissolved copper nitrate and carbohydrazide give small-sized particles in presence of alkali metal halides at lower temperature than the traditional method of preparation. This new route takes less than five minutes and requires much less energy. The optical and luminescence characteristics of ZnS:Cu,Al phosphor thus prepared were found to be enhanced significantly. Carbohydrazide acted as fuel at $500^{\circ}C$ with rapid heating and then the phosphors obtained were heated at $900^{\circ}C$ in an inert atmosphere for 3hrs to get better luminescent properties.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.12
• /
• pp.1715-1718
• /
• 2002

Treatment of ethyl 5-hydroxy-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxylate (1a) with hydrazine hydrate in ethanol gave the carbohydrazide 2,. Some derivatives of the latter compound have been synthesized. Also, 6-acetyl-3,4-diphenyl-5-hydroxythieno[2.3-c]pyridazine (1b) was subjected to some reactions to produce other new thienopyridazine derivatives.

• Journal of the Korean Ceramic Society
• /
• v.38 no.8
• /
• pp.765-770
• /
• 2001

광촉매용 ZnO 나노크기의 분말은 시작원료와 연료의 종류에 따라 용액연소법에 의해 제조되었다. 결정상은 XRD로부터 확인할 수 있었으며 분말의 하소온도는 TG 분석으로부터 결정되었다. 분말의 비표면적은 BET 법에 의해 측정되었으며 평균입자크기와 형태를 SEM과 TEM으로부터 조사하였다. 또한 분말의 순도를 조사하기 위해 적외선 흡수스펙트럼을 측정하였으며 광촉매 효율로서 은이 첨가된 사진현상액을 이용하여 은의 수거율을 측정하였다. 용액연소법으로 제조한 경우 시작원료와 연료에 관계없이 단상의 ZnO 분말을 쉽게 얻을 수 있었다. 그러나 합성된 ZnO 분말의 입자크기와 형태는 연료의 종류에 따라 서로 다르게 보였다. 특히, 연료로 glycine을 사용한 경우, ZnO 분말의 입자 형태는 균일한 나노 크기의 구형이었으나 carbohydrazide을 사용한 경우에는 판상과 같은 형태를 보였다. 이러한 결과를 기초로 하여 시작원료와 연료로 Zn(OH)$_2$와 glycine을 사용하여 합성된 ZnO 분말이 우수한 분말 특성을 보였으며 75nm의 입자크기와 94$m^2$/g의 비표면적을 보였다. 또한 사진현상액에 존재하는 은이 3분 이내에 완전히 제거되는 우수한 광촉매 성질을 보였다.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.2
• /
• pp.575-582
• /
• 2012

In continuance of our search for newer antihepatotoxic agents some novel thiazolidinone derivatives containing 1,4-benzodioxane ring system were synthesized starting from 2,3-dihydro-1,4-benzodioxane-2-carbohydrazide. The synthesized compounds were evaluated for antihepatotoxic activity against $CCl_4$-induced hepatotoxicity in rats. Among them some compounds have shown significant antihepatotoxic activity comparable to standard drug silymarin.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.126-126
• /
• 2003

산화아연은 높은 열전도도와 열용량을 갖으며, 결정 부피의 44%만이 아연 및 산소 이온으로 채워져 있어 결함의 생성이 다양하여 여러 가지 전기적, 광전기적, 촉매 특성등을 부여할 수 있어 산업전반에 널리 이용되고 있다. 따라서, 본 연구에서는 초음파 분무 연소합성법을 이용하여 Zinc nitrate hexahydrate를 산화제로, Carbohydrazide를 환원제로 사용하여, 연소합성을 위한 에너지를 최대희 얻기 위해 산화수와 환원수의 비율이 1:1이 되게 조절하여 전구체의 산화ㆍ환원 반응을 이용하여 액적의 체류시간, 농도, 온도, filtering 효과등을 조절하면서 액적 단위로 연소반응을 유도함으로써 부가적인 하소과정이 필요없이 상전이가 완료된 구형의 나노크기 ZnO 분말을 in-situ로 제조하여 입자의 크기와 형 태, 결정상등을 분석하였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.1013-1016
• /
• 2003

A new route for the synthesis of silver doped of zinc sulfide phosphor by combustion method has been investigated. Silver nitrate was decomposed with urea or carbohydrazide to give small size particles in presence of alkali metal halides at low temperature compared to the conventional method. The high temperature inherent to the highly exothermic nature of redox reaction leads to well-crystallized powder in short time. The phosphors thus obtained were further heated at $1050^{\circ}C$ in an inert atmosphere for 3hrs to get better luminescence properties.