You will be shown an abstract from a materials science research paper. Your task is to extract all synthesis operations described in the abstract into a structured JSON format. Your output should be a JSON array. Each entry in the array should be a JSON object describing a single synthesis operation. This object should have the following fields:

- "trigger": A verbal predicate indicating a synthesis operation. This should be a string extracted directly from the abstract.
- "arguments": An array of arguments specifying aspects of the synthesis operation. Each entry in the array should be a length-2 array formatted as [<argument_text>, <argument_type>]. The `argument_text` should be a string extracted directly from the abstract. The `argument_type` should be one of the following types: ["Recipe_Precursor", "Atmospheric_Material", "Participant_Material", "Recipe_Target", "Solvent_Material"].

For instance, suppose an excerpt from the abstract reads:

Tetraethoxysilane (TEOS, 98%) and cetyltrimethylammonium bromide (CTAB, 98%) were purchased from Fluka. The MTTZ-siloxy derivative (triethoxysilyl-propyl-5-mercapto-1-methyl-tetrazole) was synthesized as previously described [38].

This excerpt includes two operations, which could be annotated as follows.

[{"arguments": [["Tetraethoxysilane", "Recipe_Precursor"], ["cetyltrimethylammonium bromide", "Recipe_Precursor"]], "trigger": "purchased"}, {"arguments": [["MTTZ-siloxy derivative", "Recipe_Target"]], "trigger": "synthesized"}]

In your response, please include the JSON and no other text.

Abstract:
10.1016/j.matlet.2012.10.091
Perovskite LaMnO3 hollow nanospheres: The synthesis and the application in catalytic wet air oxidation of phenol

All the chemicals used are A.R. grade. In a typical process, 2.5 mmol La(NO3)3*6H2O, 2.24 g 50% Mn(NO3)2 solution (containing 7 mmol Mn2+), 10 mmol citric acid (C6H8O7*H2O), 45 mmol urea and 1.0 g P123 were dissolved with a mixed solvent containing 2 mL ethanol, 8 mL ethylene glycol and 2 mL H2O. After being stirred for 5 h, the obtained solution was transferred into a 70 mL stainless autoclave, and heated at 100 degC for 48 h. The solid product was washed and collected by centrifugation, then dried overnight at 60 degC. This gray product was calcined at 600 degC for 8 h in air flow to convert it to LaMnO3.
[{"arguments": [["H2O", "Solvent_Material"], ["P123", "Participant_Material"], ["La(NO3)3*6H2O", "Recipe_Precursor"], ["solvent", "Participant_Material"], ["ethylene glycol", "Solvent_Material"], ["Mn(NO3)2", "Recipe_Precursor"], ["ethanol", "Solvent_Material"], ["urea", "Participant_Material"], ["citric acid", "Participant_Material"]], "trigger": "dissolved"}, {"arguments": [["solution", "Participant_Material"]], "trigger": "transferred"}, {"arguments": [["product", "Participant_Material"]], "trigger": "washed"}, {"arguments": [["product", "Participant_Material"], ["air", "Atmospheric_Material"]], "trigger": "calcined"}]