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.jallcom.2016.05.264
Multi-shelled NiO hollow spheres: Easy hydrothermal synthesis and lithium storage performances

Synthesis of multi-shelled NiO hollow spheres: In a typical experiment, 0.01 mol d-glucose and 0.02 mol Ni(NO3)2*6H2O were dissolved in 50 ml utrapure water. Then, the solution was homogenized by vigorous stirring. After stirring for 30 min, the resultant mixture was transferred to a 100 ml Teflon-lined autoclave followed by hydrothermal treatment at 180 degC for 20 h. The obtained products were washed and filtered off several times using utrapure water and ethanol successively, and finally dried in a vacuum oven at 80 degC for 12 h. After synthesis, the products were subjected to annealing at 270, 350, 430 or 550 degC for 3 h in air with a heating rate of 2 degC min-1 from room temperature to obtain multi-shelled NiO hollow spheres with a controlled number of shells (solid NiO sphere, double-, triple- and quadruple/quintuple-shelled NiO hollow sphere, respectively).
[{"arguments": [["Ni(NO3)2*6H2O", "Recipe_Precursor"], ["d-glucose", "Participant_Material"], ["water", "Solvent_Material"]], "trigger": "dissolved"}, {"arguments": [["solution", "Participant_Material"]], "trigger": "homogenized"}, {"arguments": [["mixture", "Participant_Material"]], "trigger": "transferred"}, {"arguments": [["products", "Participant_Material"]], "trigger": "washed"}, {"arguments": [["ethanol", "Solvent_Material"], ["water", "Solvent_Material"]], "trigger": "filtered"}, {"arguments": [["products", "Participant_Material"]], "trigger": "subjected"}, {"arguments": [["air", "Atmospheric_Material"]], "trigger": "annealing"}]